Fluid-meter.



No. 790,888. PATENTED MAY 30, 1905. W. ITEMS.

FLUID METER.

` APPLIOATION FILED MAE. 1B, 1901.

2 SHEETS-SHEET 1.

PATENTE) MAY so, 1905.

W. mams. Emma METER.

ATON FILED MAR. 18,1901.

APYLIO ZSHBBTS-SHEBT 2.

NITED STATES Patented May 30, 1905.

PATENT OFFICE.

FLUID-METER.

SPECIFICATION forming part f Letters Patent No. 790,888, dated May so,1905.

Anplication filed March 18,1901. Serial No. 51,650.

To all whom, it 17u/.y concern.-

Be it known that LVVAL'IER FnRRIs. a citi- Zen of' the United States,residing in Philadelphia, Pennsylvania, have invented certainImprovements in Fluid-Meters, of which the following is a specification.

The object of my invention is to so construct a fluid-meter as toregister with accuracy fluid passing through the meter-tube at a lowervelocity than the minimum rate at which with the present types of metersthe flow can be registered with any approach to accuracy.

My invention consists in part in the application of a secondary passageor shunt-tube to a conduit conveying a Huid in condition of full flow,said secondary passage being so connected with the main conduit vthat aportion of the Huid will pass through the secondary passage inaccordance with well-known hydraulic laws. The secondarypassage isformed with a constricted portion or throat in such manner that thevelocity of the fluid passing through this throat must exceed thevelocity of' flow in the main tube at either the entrance to or exitfrom the secondary passage.

My invention further consists in certain conformations of' the mainconduit and secondary passage and in certain arrangements of saidsecondary passage in respect to the main conduit in order to obtain thedesired high velocity through the throat in the secondary passage withthe least possible frictional loss; and it also consists in methods ofapplying measuring devices to thc. throat in the secondary passage andto some other point in the apparatus or to the throat only in some casesin such manner as to obtain an accurate measurement of the total amountof liuid passing through the main conduit.

For convenience I will hereinafter term the secondary passage theshunt-tube and its throat the shunt-throat and will designate the mainpassage or conduit the main tube and where it also has a constrictionwill call the latter the main throat.

The forces tending to induce the flow through the shunt-tubeare higherstatical pressure in the main tube at the entrance to said shunt-tubethan at the exit and kinetic energy stored in the flowing fluid as itenters the mouth of the shunt-tube or in cases where the static pressureat the exit of the shunttube is greater than at its entrance suchkinetic energy of the entering fluid as will be suflicient to overcomesuch excess of static pressure.

In the accompanying drawings, Figure l is aside elevation, partly brokenaway and illustratin'g a shunt-tube and mercury-gage applied to a maintube of' uniform diameter in accordance with my invention. Fig. 2 is asimilar view, but illustrating the direct application of a mechanicalmeasuring apparatus to the shunt-tube. Fig. 3 is a transverse section ofFig. 2. Fig. 4 is a sectional View illustrating the application of theshunt-tube to a Venturi tube and also showing a series of gages forindicating pressures at different points in the main and shunt tu bes.Fig. 5 is a View showing the arrangement ot' the shunt-tube on theoutside of a main tube such as shown in Fig. 1. Fig. 6 is a view showingthe application of the outside shunt-tube to a Venturi tube. Fig. 7 is aView illustrating the shunt-tube disposed so as to cause flow throughthe same in a direction the reverse of its flow through the main tube.Fig. 8 is a view illustrating a different means of' communicationbetween the outside shunt-tube and the main tube than those beforeshown. Figs. 9 and 10 are views showing shunt-tubes communicating withVenturi tubes in a manner the'reverse of those shown in the otherfigures. Fig. 11 is a sectional view of' a Venturi tube with shunt-tubeand series of gages similar to those shown in Fig. 4, but withPitot-tube connections; and Fig. 12 is a sectional view of' a Venturitube, showing special forms of feed and discharge for the shunt-tube.

It is a well-known fact that the pressure of the contained fluid againstthe walls of a conduit diminishes as the velocity of' flow of the fluidthrough said conduit increases and, conversely, such decrease of staticpressure being due to its conversion into kineticenergy stored in themore rapidly moving fluid, and if' the velocity be again diminished toits original value the static pressure will reappear less the amountrequired to perform the IOO work represented by frictional resistancebetween the particles ot' the fluid and between the iuid and the wallsof the conduit. Hence in a conduit graduallydecreased in area from 'w tow', Fig. 4, and thence gradually increased to its original area at '102there will be during the How a fall of pressure at w, represented by thedifference in the height of the mercury columns in the gage and a lesserfall of pressure at wz, represented by the dierence in the height'of themercury columns in the gage ai. Both of these pressure diferences arevfound by experiment to be within certain limits nearly proportional tothe square of the velocities existing at the given cross-sections duringvarious rates of flow, and in a well-designed tube with water as thefluid the lost head represented by the gage is about one-sixth of thehead represented by the gage This form of tube, called the Venturi tube,is already used as a watermeter, the means of discovering the existingVelocity within the tube being the diference of pressure represented bythe gage w; but the usefulness of this form of meter, as well as of thePitot tube form of meter, described in my application Serial No.722,082, is limited, on the one hand, by the very slight difference ofpressure acting' on the differential gage when the velocity of Howthrough the meter is small, and, on the other hand,

by the excessive lost head when the velocity becomes too great. Hence ithas been found in practice 'that the limits of velocity through suchmeters range from about three feet to about forty feet per second.

Below three feet per second the measure;

ment becomes inaccurate, as the pressure to be measured at this rate offlow only represents about one one-hundredth of one foot of mercury inordinary cases, while if the velocity exceeds forty feet per second thelostA head is no longer proportional to the square of velocity, butrises much more rapidly until it becomes almost impossible to get morewater through the meter; hence the desirability ot' a device which willincrease the head m without materially increasing the lost head rc'. Toaccomplish this, I employ the shunttube already mentioned, which divertsa small quantity of the fiuid from the main tube, temporarily raises itto a higher, velocity than is attained in said main tube, and thenreturns it to the latter. 4As this higher velocity is given only to afraction of the total current, the excess of lost head in this fractionis scarcely felt when distributed throughout the larger mass of fluidpassing through ,the main tube, and as the high velocity ofthelshuntcurrent is proportional to the lower velocity in the main tubethroughout the range of the meter any velocity existing in the mainthroat or tube can be ascertained by reading the gage operating inconnection with the shunt-throat, for it' the apparatus is iirst testedto find the head represented by said gage for any known velocity thevelocity for any other observed head can be readily calculated.

An examination of Fig.4, with the comparative heads of the threeditlierential gages,will give a clear idea of the principles on whichthe action of the shunt-tube depends. In this case we have a Venturitube l, containing a shunt-tube 2, with its receiving end or mouth in aportion of the tube having full area and its delivery end at or aboutthe constricted throat 3 of the Venturi tube, this shunt-tube likewisehaving a constricted throat 4,which is in communication with one leg ofa gage m2, the other leg of said gage being in communication with afull-area portion ot' the Venturi tube.

Considering the main tube alone, it appears that the velocity may betemporarily raised until it shows the Venturi head represented by gageand then lowered again to its original value with a loss oi only thelost head represented by gage which, as already stated, is approximatelyone-sixth of the Venturi head.

With the shunt-tube located as shown the Venturi head of the main tubebecomes the lost head of the shunt-tube-that is to say, the differenceof pressure between the two ends of the shunt-tube is about six timesthe difference between the pressures in thel portions w and 102 of themain tube. Hence if the frictional resistance in the two tubes is thesame the shunt-head represented at m2 will be six times its lost head,(which is the Venturi head ag) just as the Venturi head is about sixtimes its own lost head, and hence the shunt-throat should beproportionedto give a velocity equal to the square root of six times thevelocity in the main throat-that is to say, about two and Jforty-fiveone-hundredths times such mainthroat velocity. full theoretical increasein shunt-throat velocity may not be attained; but no difficulty will beexperienced in obtaining such a considerable fractional part of thetheoretical increase as will make the sh unt-head represented at :102 atleast three times the corresponding Venturi head represented at When theshunt-tube is placed, as shown in Fig. 4, with its ends indifferent-sized sections of the main tube, I make the cross-sectionalarea of the ends of the shunt-tube proportionate to the correspondingsectional areas of the main tube, and while I prefer always to locatethe shunt-tube in the main tube and to dispose its delivery end at thecontracted throat of 'such main tube this construction and arrangementis not essential to the main embodiment of my invention. For instance,in

Figs. 1, 2, and 5 I have shown the shunt-tube combined with a main tubeof uniform area throughout, the flow in the shunt-tube in these casesbeing due to the kinetic energy of the iiuid, slightly assisted by thefall otl pressure IOO In practice, however, this TIO in the main tubedue to frictional resistance between the points w and 102, whichfriction may be increased to any desired extent by interposingobstacles-such as perforated plates y, Fig. 5, or the like-in the maintube between the points w and 102. I prefer, however, to adopt thesimpler and more desirable hydraulic expedients which I have shown,these being designed with reference to the prime consideration in thisclass of Work-namely, the production of an accurate meter which willcause the least possible resistance to the flow through it.

The shunt-tube may also, if desired, extend to the outside of the maintube, as shown in Figs. 5, 6, 7, 8, l0, and 12, and various forms ofdevices for measuring the head at the shuntthroat may be adopted-such,for instance, as the mercury-gage shown in most ofthe figures ofthedrawings--or I may adopt means for effecting direct mechanicalmeasurementgas, for instance, a helical wheel 5 or other rotat- ,ingdevice located in the shunt-throat and carried by a shaft 6, connectedby appropriate gearing to any suitably-located register-as, forinstance, in Figs. 2 and l2.

In that form of meter shown in Fig. 7 the flow through the shunt-tube isthe reverse of the flow through the main tube and is caused almostentirely by the kinetic energy of the entering water, slightlyA aided bysuction at the exit, due to the flow of the main current.

Fig. 8 shows a form of my improved meter in which the shunt-flow iscaused almost entirely by the fall of pressure at the main throat, beingslightly assisted by the inclination of' the openings 7, through whichthe main tube communicates with pressure-cham bers 9 at the oppositeends of the external shunt-tube 2, and, further, by the frictional lossin the main tube between these two chambers.

In that form of my improved meter shown in Figs. 9 and l0 the shunt-flowis caused mainly by kineticenergy in the entering water, assisted by thefrictional losses inY the main tube between the entrance to and exitfrom the shunt. In these meters the static pressure is greater at theexit than at the entrance to the shunt, and this excess operates againstthe shunt-flow. Hence a rapid How through such shunt could only beobtained by placing excessive frictional resistance, such as theobstruction y, Fig. 10, in the main passage. Therefore while I haveshown these two forms of meter as embodying the main principle of myinvention they have not the same effectiveness as the other forms ofmeter shown, whose use is therefore to be preferred. The meter shown inFig. l() also illustrates annular forms of entrance to and exit from theshunt, which in their hydraulic effect are similar to the ordinarynozzles, such as are shown in Fig. 5, and this form of entrance and exitfor the shunt may be preferred in certain cases for reasons of'construction,

such as lesser possibility of clogging, &c. Hence they may be used inmost of the other forms of meter in which an external shunttube isemployed.

Fig. 11 shows three different methods of attaching a Pitot tube and astaticpressure tube to the meter, all giving the same head on thedifferential gages, neglecting the element of friction. This is due tothe fact already noted that the sum of the static and kinetic pressuresremains constant, neglecting friction, through all velocity changes.

In those forms of my improved meter shown in Figs. 7 and l2 theshunt-tube both receives the shunt-current from and returns it to thesame cross-section in the main throat, the force impelling theshunt-current being the same substantially as in the constructions shownin Figs. 4 and 6, supposing that there are the same velocities throughthe main throat.

In all cases the force tending to drive the water into the mouth of theshunt-tube comprises two elements-the static pressure and the kineticenergy in the fluid-and, as is well known, the sum of these forces atany section of a conduit is equal to their sum at any succeeding sectionless the loss caused by friction between the two sections, andexperiment has shown that the loss by friction in a convergingajutage-as, for instance, the part between w and w' in Fig'. 4 is verysmall. Hence if it is desirable for any reason the entrance to the shuntmay be placed at the main throat if the exit be also retained at thesame place.

' Having thus described my invention,I claim and desire to secure byLetters Patentl. The combination, in a fluid-meter, of a main tube witha shunt-tube of the Venturi type of less area than the main tube, andthrough which the fluid Hows with greater velocity than that of the flowthrough the main tube, and means, acted upon by the fluid at thecontracted throat of the shunt-tube, for measuring the velocity of thefluid at said contracted throat, substantially as specified.

2. The combination in a fluid-meter, of a main tube, a shunt-tube of theVenturi type located wholly within said main tube, and means formeasuring the velocity of the fluid flowing through the contractedthroat of said shunt-tube, substantially as specified.

3. The combination, in a fluid-meter, of a main tube of the Venturitype, a shunt-tube also of the Venturi type, such shunt-tube being ofless area than the main tube and through which the fluid fiows withgreater Velocity than that of the flow through the main tube, and means,acted upon by the fluid at the contracted throat of the shunt-tube, formeasuring the velocity of the fluid at said contracted throat,substantially as specified.

4:. The combination in a fluid-meter, of a main tube of the Venturi typehaving a con- IOO tracted throat, a shunt-tube also of the Venturi typeand disposed so as to deliver at the contracted throat of the mainVenturi tube, and devices for measuring the velocity of the fluidflowing through said shunt-tube, substantially as specified.

5. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube located inside of said maintube and likewise having a contracted throat, and means for measuringthe velocity of' the fluid flowing through said shunt-throat,substantially as specified.

6. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube located inside of said maintube, and also having a contracted throat, said shunt-tube delivering atthe contracted throat of the Venturi tube, and means for measuring thevelocity of the fluid flowing through said shunt-throat, substantiallyas specified.

7. The. combination, in a fluid-meter, of a main tube, a shunt-tube ofthe Venturi type, of' less area than the main tube and through which thefluid flows with greater velocity than that of the fiow through the maintube, and gage-tubes for measuring the velocity of the fluid flowingthrough the shunt-tube, one

of said gage-tubes communicating with the fluid at the contracted throatof said shunttube, and the other communicating with the fluid at someother point in its flow, substantially as specified.

8. The combination in a fluid-meter, of a main tube, a shunt-tube of theVenturi type located wholly within said main tube, and gagetubes formeasuring the velocity of' the fluid flowing through said shunt-tube,substantially as specified.

9. lThe combination, in a fluid-meter, of a main tube of the Venturitype, a shunt-tube also of the Venturi type, said shunt-tube being ofless area than the main tube and through which the fluid flows withgreater velocity than that of the flow through the main tube, andgage-tubes for measuring the Velocity of the fluid passing through -thecontracted throat of said shunt-tube, substantially as specified.

10. The combination in a fluid-meter, of a main tube of'. the Venturitype having a contracted throat, a shunt-tube also having a contractedthroat and disposed so as to deliver at the contracted throat of theVenturi tube, and gage-tubes for measuring the velocity of the fluidflowing through said shunt-throat, substantially as specified.

11. The combination in a fluid-meter, of' a main tube of the Venturitype having a contracted throat, a shunt-tube located inside of saidmain tube and likewise havinga contracted throat, and gage-tubes formeasuring the velocity ofthe fluid owing through said shuntthroat,substantially as specified.

12. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube located inside of' `said maintube, and also having' a contracted throat, said shunt-tube deliveringat the contracted throat of the Venturi tube, and gagetubes formeasuring the velocity of the fluid flowing through said shunt-throat,substantially as specified.

13. The combination in a fluid-meter, of a main tube, with a shunt-tubeof the Venturi type, and gage-tu bes communicating in diierentdirections with the flowing fluid for measuring the velocity of thefluid flowing through the contracted throat of said shunt-tube, one ofsaid gage-tubes communicating with the fluid at the contracted throat ofthe said shunttube, substantially as specified.

14. The combination in a fluid-meter, of a main tube, a shunt-tubelocated within said main tube and having a contracted throat, and

gage-tubes communicating in different direc-l tions With the flowingfluid for measuring the velocity of the fluid flowing through saidshunt-throat, substantially as specified.

15. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube also having a contractedthroat, and gage-tubes communicating in different directions with theflowing fluid for measuring the velocity of the fluid flowing throughsaid shunt-throat, substantially as specified.

16. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube also having a contracted throatand disposed so as-to deliver at the contracted throat of the Venturitube, and gage-tubes communicating in dierent directions with theflowing fluid for measuring the velocity of the fluid flowing throughsaid shuntthroat, substantially as specified.

17. The combination in a fluid-meter, of' a main tube of the Venturitype having a contracted throat, a shunt-tube located inside of saidmain tube and likewise havinga contracted throat, and gage-tubescommunicating in different directions with the flowing fluid formeasuring the velocity of' the fluid flowing through said shuntthroat,substantially as specified.

18. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube located inside of said maintube, and also having a contracted throat, said shunt-tube delivering atthe contracted throat of the Venturi tube, and gagetubes communicatingin different directions with the flowing fluid for measuring thevelocity of the fluid flowing through said shuntthroat, substantially asspecified.

19. The combination in a fluid-meter, of a main tube, with a shunt-tubehaving a contracted throat, and gage-tubes for measuring the velocityof' the fluid flowing through said TOO IIO

shunt-throat, one of said tubes communicating with the uid at theshunt-throat, and the other with another portion of the llowing Huid,substantially as specied.

20. The combination in a fluid-meter, 'ot' a main tube, a shunt-tubelocated within said main tube and having a contracted throat, andgage-tubes for measuring the velocity of the fluid flowing through saidshunt-throat, one of said tubes communicating with the fluid at theshunt-throat, and the other with another portion of the lowing luid,substantially as specified.

21. `The combination in a uuid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube also having a contracted throatand disposed so as to deliver at the contracted throat of the Venturitube, and gage-tubes for measuring the velocity of the luid flowingthrough said shunt-throat, one of said tubes communicating with thefluid at the shunt-throat, and the other with another portion of theflowing fluid, substantially as speeilied.

22. The combination in a fluid-meter, of a l main tube of the Venturitype having a contracted-throat, a shunt-tube located inside of saidmain tube and likewise having a contracted throat, and gage-tubes formeasuring the velocity of the luid flowing through said shunt-throat,one of said tubes communicating with the fluid at the shunt-throat, andthe other with another portion of the flowing fluid, substantially asspecified.

23. The combination in a fluid-meter, of a main tube of the Venturi typehaving a contracted throat, a shunt-tube located inside of said maintube, and also having a contracted throat, said shunt-tube delivering atthe eontraeted throat of the Venturi tube and gagetubes for measuringthe velocity of the lluid flowing through said shunt-throat, one of saidtubes communicating with the fluid at the shunt-throat, and the otherwith another portion of the flowing fluid, substantially as specified.

In testimony whereof I have signed my name to this specification in thepresence of two subseribing witnesses.

WALTER FERRIS.

Witnesses F. E. BECHTOLD, Jos. H. KLEIN.

